D&D 5E Perception, Passive Perception, and Investigation

[billd91]

Passive skills are poorly understood because they never actually put the rules down on how to use them. I'm of the opinion that this was intentional in order to allow each group to decide how to use them, despite JC's insistence on how they're "the floor" for those skills. I use the Mike Mearls of method of rolling a die against the PCs passive skill, allowing a level of randomness while still rewarding spending resources on passive bonuses. One nice thing about this is that you can then expand the passive skills to include the knowledge skills (arcana, history, etc.) so that you can roll a passive check to give out some info before the players think to ask.

This is one instance where pulling more from 4e might have helped. Here's what the 4e PH has to say:

Checks without Rolls
In some situations, luck does not affect whether you succeed or fail. In a calm environment (outside an encounter), when dealing with a mundane task, you can rely on sheer ability to achieve results.
Take 10
When you’re not in a rush, not being threatened or distracted (when you’re outside an encounter), and when you’re dealing with a mundane task, you can choose to take 10. Instead of rolling a d20, determine your skill check result as if you had rolled the average (10). When you take 10, your result equals your skill modifiers (including one-half your level) + 10. For mundane tasks, taking 10 usually results in a success.
Passive Checks
When you’re not actively using a skill, you’re assumed to be taking 10 for any opposed checks using that skill. Passive checks are most commonly used for Perception checks and Insight checks, but the DM might also use your passive check result with skills such as Arcana or Dungeoneering to decide how much to tell you about a monster at the start of an encounter.
For example, if you’re walking through an area you expect to be safe and thus aren’t actively looking around for danger, you’re taking 10 on your Perception check to notice hidden objects or enemies. If your Perception check is high enough, or a creature rolls poorly on its Stealth check, you might notice the creature even if you aren’t actively looking for it.

5e largely dispenses with the need for a player to Take 10 by giving the DM the authority to declare success/failure outright when the outcome shouldn't really be in doubt. The passive check description here is, I think, nice and clear - clarity of the rules being one of 4e's general strengths. And notice the idea of passive knowledge checks here as well, one of the reasons why I'm specifically responding to your post, Shiroiken.
One drawback to the whole Taking 10/passive score issue, however, is the rules for them developed in editions where opponents who were level-appropriate were likely to keep up with a PCs skill value, making Taking 10/passive checks less of a likely success. They were great for weaker opponents, relatively mundane challenges but deliberately accepted a half-assed result that left half of the d20's results, the higher half, completely out of reach. PCs couldn't count on a lucky die roll to find a particularly challenging skulker or trap. That doesn't seem to be as likely with 5e with more PCs likely to be proficient in perception compared to monsters significantly skilled in stealth, or vice versa. The passive perception score tends to do really well by comparison.

 

[Charlaquin]

This is one instance where pulling more from 4e might have helped. Here's what the 4e PH has to say:



5e largely dispenses with the need for a player to Take 10 by giving the DM the authority to declare success/failure outright when the outcome shouldn't really be in doubt. The passive check description here is, I think, nice and clear - clarity of the rules being one of 4e's general strengths. And notice the idea of passive knowledge checks here as well, one of the reasons why I'm specifically responding to your post, Shiroiken.
One drawback to the whole Taking 10/passive score issue, however, is the rules for them developed in editions where opponents who were level-appropriate were likely to keep up with a PCs skill value, making Taking 10/passive checks less of a likely success. They were great for weaker opponents, relatively mundane challenges but deliberately accepted a half-assed result that left half of the d20's results, the higher half, completely out of reach. PCs couldn't count on a lucky die roll to find a particularly challenging skulker or trap. That doesn't seem to be as likely with 5e with more PCs likely to be proficient in perception compared to monsters significantly skilled in stealth, or vice versa. The passive perception score tends to do really well by comparison.

I actually rather think that looking to how 4e handled passive checks causes undue confusion. Passive checks in 4e were used for resolving opposed checks when you aren’t actively using a skill. Conversely, so-called passive checks in 5e are explicitly for use when a task is being performed repeatedly over time.

Certainly, one can choose to run passive checks in 5e more like how they were used in 4e, but I believe that is quite the opposite of how the rules describe them.

 

[Xetheral]

Personally, I use a couple of houserules to avoid some of these issues.

First, I let Observant give advantage on active Perception and Investigation checks, in addition to passive checks. I do this because I don't want the utility of the feat to depend heavily on whether I call for an active check or use a passive check. (As a general principle, I don't want the outcome of an in-game action to be dependent on the choice between two different resolution methods.)

Second, in addition to deduction, I let Investigation also apply to situations covered by the old Gather Information skill, and I also let it work as a general-purpose Research skill (broader than just finding hidden fragments of knowledge). I find this gives the Investigation skill enough alternative uses that I don't have to go out of my way to design traps and other game elements in a way that makes Investigation useful--instead I can just design traps with the builder's IC goals/resources in mind.

 

[billd91]

I actually rather think that looking to how 4e handled passive checks causes undue confusion. Passive checks in 4e were used for resolving opposed checks when you aren’t actively using a skill. Conversely, so-called passive checks in 5e are explicitly for use when a task is being performed repeatedly over time.

Honestly, those are pretty much the same thing. You're never not perceiving the world around you, giving you a chance to spot some hostile creature stalking you. When someone is lying to you, you're never not observing them and capable of judging whether or not they're lying. You just may not be putting as much focus into it (hence, giving up the upper half of the d20's potential results) as when you're actively engaging in it.
What the 4e rules do is indicate fairly clearly when the passive score is used vs when the rolled result is used. The passive isn't a floor to use if the actively used check comes up low on the d20.

 

[Charlaquin]

Honestly, those are pretty much the same thing.

I don’t think they are at all. In 4e, use of passive checks is automatic and applied when you aren’t using the skill actively. In 5e, use of a “passive” check is specifically called for by the DM when a task is performed over and over again (and has a risk of and consequence for failure.) It is much closer to 4e’s version of taking 10 than to 4e’s passive check.

You're never not perceiving the world around you,
giving you a chance to spot some hostile creature stalking you. When someone is lying to you, you're never not observing them and capable of judging whether or not they're lying. You just may not be putting as much focus into it (hence, giving up the upper half of the d20's potential results) as when you're actively engaging in it.

Well, as someone with ADHD who is constantly on their phone (mostly using it to post on gaming forums), I disagree that you’re always aware of the world around you. But, setting that aside, if you do want to use that as a basis to form your ruling on passive perception, that’s fine, but I don’t think it’s consistent with how the rules of 5e describe using them.

What the 4e rules do is indicate fairly clearly when the passive score is used vs when the rolled result is used. The passive isn't a floor to use if the actively used check comes up low on the d20.

Right, but I think the 5e rules describe how to use passive checks quite clearly as well, it just happens to be different than how the 4e rules describe using passive scores. The only thing that’s unclear about passive checks in 5e is that the name doesn’t really line up well with how the rules say to use them. I think if they had called the rule “taking 10” instead, no one would find it confusing at all.

 

[iserith]

Personally, I use a couple of houserules to avoid some of these issues.

First, I let Observant give advantage on active Perception and Investigation checks, in addition to passive checks. I do this because I don't want the utility of the feat to depend heavily on whether I call for an active check or use a passive check. (As a general principle, I don't want the outcome of an in-game action to be dependent on the choice between two different resolution methods.)

Second, in addition to deduction, I let Investigation also apply to situations covered by the old Gather Information skill, and I also let it work as a general-purpose Research skill (broader than just finding hidden fragments of knowledge). I find this gives the Investigation skill enough alternative uses that I don't have to go out of my way to design traps and other game elements in a way that makes Investigation useful--instead I can just design traps with the builder's IC goals/resources in mind.

For Observant, I run it as written, but the key thing is that in my games, if you want to be the guy or gal who notices all the threats (monsters, traps), that's the only task you're doing, unless you're a ranger in favored terrain. You can't navigate, draw a map, forage, track, or search for secret doors. I take care to ensure that these activities are valuable in context so that there's a meaningful choice as to what to do. Source maps are worth gold. Navigating keeps the party from getting lost and going off course. Foraging keeps food and water stocked or turns up valuable trade goods. Tracking allows the party to look for trouble (XP!) or avoid it. Secret doors always lead to treasure, short cuts around dangers, or safe places to rest. So yeah, be Observant, whip out that 20+ PP! But know that you probably won't be doing this other stuff. Plus depending on your marching order, you might not be able to notice threats at the front of the party unless you're in the front rank. That means you're likely the meat shield for people behind you.

I think a character trying to influence locals to giving up useful information would be fine for a Charisma check and a player establishing the character is working to deduce who to talk to and what the rumors all mean could be a Charisma (Investigation) check, if a check was called for. I find I don't have to go out of my way to design traps and secret doors though because that's firmly in the scope of Dungeons & Dragons anyway.

 

[Charlaquin]

Personally, I use a couple of houserules to avoid some of these issues.

First, I let Observant give advantage on active Perception and Investigation checks, in addition to passive checks. I do this because I don't want the utility of the feat to depend heavily on whether I call for an active check or use a passive check. (As a general principle, I don't want the outcome of an in-game action to be dependent on the choice between two different resolution methods.)

I think this issue could also be resolved by being very consistent with when you call for rolls vs. when you call for passive checks, and being very transparent with the players about when you use each. Not that the house rule isn’t also a good one of course. I might go for advantage on rolled checks instead of +5 on them, but the concept is solid.

Second, in addition to deduction, I let Investigation also apply to situations covered by the old Gather Information skill, and I also let it work as a general-purpose Research skill (broader than just finding hidden fragments of knowledge). I find this gives the Investigation skill enough alternative uses that I don't have to go out of my way to design traps and other game elements in a way that makes Investigation useful--instead I can just design traps with the builder's IC goals/resources in mind.

I call for ability checks and let the player determine if any of their proficiencies are applicable. But I do think there are a lot of information gathering and research related tasks where investigation proficiency seems like it would be very applicable.

 

[Li Shenron]

Passive checks are just like any other check, only relevant when the DM calls for them. They are not always on.

This.

 

[Xetheral]

For Observant, I run it as written, but the key thing is that in my games, if you want to be the guy or gal who notices all the threats (monsters, traps), that's the only task you're doing, unless you're a ranger in favored terrain. You can't navigate, draw a map, forage, track, or search for secret doors. I take care to ensure that these activities are valuable in context so that there's a meaningful choice as to what to do. Source maps are worth gold. Navigating keeps the party from getting lost and going off course. Foraging keeps food and water stocked or turns up valuable trade goods. Tracking allows the party to look for trouble (XP!) or avoid it. Secret doors always lead to treasure, short cuts around dangers, or safe places to rest. So yeah, be Observant, whip out that 20+ PP! But know that you probably won't be doing this other stuff. Plus depending on your marching order, you might not be able to notice threats at the front of the party unless you're in the front rank. That means you're likely the meat shield for people behind you.

I think a character trying to influence locals to giving up useful information would be fine for a Charisma check and a player establishing the character is working to deduce who to talk to and what the rumors all mean could be a Charisma (Investigation) check, if a check was called for. I find I don't have to go out of my way to design traps and secret doors though because that's firmly in the scope of Dungeons & Dragons anyway.

That's cool. Thanks for sharing!

Personally, I find my houserules helpful at my table partially because I run a very player-driven, game with a heavy emphasis on simulation. (Those two go together--the heavy emphasis on simulation makes the game world more predictable, which in turn gives the players more agency to control their influence on the game world.)

So some of the techniques you use at your table to make the written rules work well are less usable/relevant at my table. Unless the party has screwed up somehow and lost the strategic initiative, there are rarely hidden threats for them to notice: they are the threat. Sure, there might occasionally be a group of bandits trying to ambush whomever comes next along the road,* but deliberate ambushes are rare, unless the PCs have let their enemies know when and where they'll be. Keeping alert while travelling is still invaluable, but I suspect there are fewer potentially hidden threats to notice at my table than at yours. Similarly, secret doors will rarely lead to treasure or places to rest at my table (they're more likely to be emergency exits, spyholes, or mere conveniences), the party will often already have purchased a map (trying to plan encounters strategically is a lot harder if you don't already know the terrain) or talked to locals in advance to get the lay of the land, and tracking isn't a source of XP since I don't award XP per-fight. (Also, XP is a purely OOC concept at my table, so seeking it out IC would be frowned on.)

(*And unless they're desperate or stupid, the bandits probably aren't going to attack a small, heavily armed group. Such targets are often dangerous, and unlikely to have much in the way of trade goods or easily marketable loot. Sure, some PCs carry godly amounts of cash, but the bandits don't know that.)

And my emphasis on simulation makes some of the abstraction in the written rules less palatable. I don't want players of Observant characters to feel like they have to deliberately frame their action declarations as a repeated task so that they can get a Passive-check-only bonus--it feels artificial and thus hampers verisimilitude. For example, why should an Observant trapfinder be better at searching for traps repeatedly than she is at searching for traps one at a time? Given my style preferences, I'd rather houserule than handwave that inconsistency.

As far as investigation, I do find myself having to go of my way to makes traps that require investigation of their mechanisms. Likely, that's because my emphasis on simulation means I'm usually going to use very simple traps that would be very easy for whomever built them to afford, and the mechanism of such traps are simple to understand. Traps with obscure mechanisms would be rare and expensive, and if well-designed would be impossible to notice in advance. Sure, I can come up with plausible explanations for badly designed (i.e. noticable) traps with complicated mechanisms, but I'm not going to do that just to make Investigation proficiency useful: I'd rather just houserule in expanded uses for the skill.

In the end, I know I'm not running a typical game. While I firmly believe my style of play was intended to be (and is!) supported by 5e, since it's not a common style I expect to need to houserule on occasion. Hence, my houserules for Observent and Investigation. They're broad enough that they could be useful in a variety of playstyles, so I shared them in case anyone concerned with the issues discussed in this thread find them a palatable solution.

 

[Charlaquin]

Is anyone else starting to get a little confused by the three separate stealth/perception threads going on at once right now?